GiDvEtTe84

Any of your guys experimented with this? Thanks for the input.

3.8TransAM

Do a search for highway Fuel and highway Spark

tons of info and various patches floating around here..

From my experience it will not gain u anything or can actually hurt your mileage unless your tune is about dead on perfect

Later
Jeremy

JPrevost

My car specific, I've seen an average 16 mpg highway without it and 20+ with it. When I was going to the extream I was able to push 23 but as of lately I've backed off a little, run cheaper gas, and have 21 to 22 mpg every trip I've made from NJ to Ohio (540 mile trip one way).
My tune has never been perfect so maybe it's just this mask that does as well as it does. Even when my BLMs were in the mid 130's, still got same milage. Then when my BLMs were in the teens and low 120's, same milage.... just goes to show you how different GM ecm's really are.

GiDvEtTe84

I see. I guess thats why GM didnt use it because of the danger of running too lean. Since every motor is different, you can tune lean cruise to your application. Thanks guys.

Pablo

iTrader: (1)

I think the reason gm didnt use it was because it raised emissions. The EPA pinko's didnt like that.

RBob

iTrader: (1)

IIRC the LO3 TBI f-bodys have lean cruise enabled from the factory.

RBob.

Twilightoptics

You are correct. Friend of mine gets darn near 28mpg on the freeway with.


Also, if you have an agressive spark table, don't use Highway spark. It's designed to add more spark and if you add more to make your total over say 41deg, the car will do weird things.

At one point when I hit highway mode it'd trigger an o2 sensor code and make the car bounce and almost die.

dimented24x7

iTrader: (2)

Yep, all the L03s had it enabled. Doesnt matter much for me, still use assloads of gas whether its enabled or disabled.

Pablo

iTrader: (1)

we'll i'll be... didn't know that. That sure explains alot of those L03 cars getting near 30 mpg though

jeepguy553

Where is the stuff for lean cruise in the 8746 $61? I don't recall having seen it. I would LOVE to boost gas mileage in my Jeep. Okay, I know it's a Jeep and is basically a rolling brick with a parachute strapped to it, but it will get about 14mpg hiway with a crapburetor on the V8. I am thinking that with the TBI I put on it, I can get this up in the low 20's.
Is there a particular flag or set of tables I can work for this feature in $61?

AustinT

Good thread, One of the reasons I am swapping to fuel injection is for the mileage gains. Today I leaned out the primaries so I would have a 14 afr down the freeway. I pulled 28 mpg with the 430 hp crate motor. I cant wait to get back to fuel injecton, should put me around 30 mpg

jeepguy553

Never mind. I found it. I hadn't ever really noticed it until now.